Characteristics

Defense

In Generation II, the Steel type was created to balance out the previously overpowered Normal and Psychic types, as both types are resisted by Steel. Although the number of Steel's resistances decreased from 11 to 10 in Generation VI, Steel remains the most resistant type. Steel types also cannot be poisoned (except by Twineedle in Generation II or if poisoned by a Pokémon with Corrosion) or damaged by a sandstorm.

Pure Steel-type Pokémon have the second-greatest amount of resistances of all type combinations. Electric/Steel is the most resistant dual type, having 11 resistances plus an immunity to Poison.

Steel-type Pokémon, on average, have the highest physical Defense among all Pokémon and among fully evolved Pokémon.

Offense

While some Pokémon resist Steel-type attacks, many of these Pokémon are weak to Ground, so combinations of Steel and Ground attacks tend to work well.

Trivia

Generation VII introduced the most Steel-type Pokémon of any generation, with thirteen, and Generation VI introduced the fewest Steel-type Pokémon since the type was created, with four.

Generation IV introduced the most Steel-type moves of any generation, with seven, and Generation VI introduced the fewest Steel-type moves since the type was created, with one.

In Generation II, the Steel type saw one type change in a Pokémon family (Magnemite and Magneton), but no change in moves. The opposite is true for the Dark type, which saw one type change in a move (Bite), but no change in a Pokémon.

Prior to Generation VI, Steel was the only type that had a non-neutral type match-up with all of the seventeen existing types, considering both the offense and defense of both types. In Generation VI, it was changed so that Steel no longer resisted Dark- or Ghost-type moves.

Each of the three starter types have a different effectiveness when attacking a pure Steel-type Pokémon (Grass does ½× damage, Water does 1× damage, and Fire does 2× damage).

More Pokémon gain the Steel type upon evolving than any other type, with a total of nine.